U.S. Pat. No. 4,655,515 discloses joining a plate-like metal ground plane of an electrical connector to a planar plastic dielectric substrate. A round boss on the substrate surface is extended through a hole in the ground plane and then the end of the boss is enlarged by being deformed by cold-staking or heat-staking as is conventionally known, to form a low profile mechanical joint without fasteners and which does not utilize adhesive material. The deformed end of the boss now extends laterally over the periphery of the hole to some extent.
It is desirable to form a metal-to-plastic mechanical joint which does not extend above the metal member surface so that the metal member surface may comprise at least a non-stubbing surface for movement of another article with respect thereto.
The present invention secures a planar metal member to the surface of a plastic member by a mechanical joint recessed into the surface of the plastic article. A pair of opposing lock tabs are stamped into the metal member at each joint location. The plastic member is molded to have a recess at each joint location within which is disposed an upstanding central boss. When the metal member is placed against the surface of the plastic member with lock tabs over the corresponding recess, a work end of a tool bends the lock tabs into the recess against preferably sloped recess sides. The tool also cold-stakes the central boss to permanently deformingly enlarge the top thereof laterally to overlap the free ends of the lock tabs which are now beside the central boss, thus forming a recessed joint.
The present invention can be used to create a commoning member for an electrical connector assembly as described in U.S. patent application Ser. No. 07/049,633 filed May 13, 1987 and assigned to the assignee hereof. The recessed joint is used to secure an end of an arcuate spring member against a surface of a plastic insert, the other end being a free end, so that when placed in a plug connector portions of the spring member are in engagement with a pair of adjacent socket contacts. Upon mating of the plug connector with a receptacle connector, a cantilever cam post of the receptacle connector is aligned with the spring member and top surface portions thereof pass over the fixed end of the spring member and over the recessed joint during mating, and a camming surface portion engages the arcuate section of the spring member and deflects the spring member out of commoning engagement with the pair of socket contacts. The free end of the spring member is retained in a recess under a bridge portion of the insert and is free to move axially in the recess to permit the arcuate spring member to be flattened during deflection, relieving stress on the recessed joint.
It is an objective of the present invention to provide a recessed mechanical joint securing a metal member to the surface of a plastic member.